In a wireless system, a wireless base station device may be configured to detect a failure in the wireless base station device and transmit a failure detection alarm to a failure monitoring device. Maintenance personnel of the wireless system specify a wireless base station device in which the failure occurred in accordance with the failure detection alarm sent to the failure monitoring device and restore the failure of the wireless base station, thereby returning the wireless system to its normal operation.
However, when a failure occurs at a place other than failure occurrence routes assumed in advance, the wireless base station device may not detect the occurrence of the failure and the failure detection alarm may not be transmitted to the failure monitoring device. A failure which occurs but is not detected and for which a detection alarm is not transmitted is called a silent failure.
When a silent failure occurs, maintenance personnel are delayed in discovering the failure since the failure detection alarm is not transmitted to the failure monitoring device. As a result, the wireless system continues its operation in an abnormal state, and a problem such that a mobile terminal device cannot communicate with the wireless base station device may be caused in a communication service.
Note that the following technology for detecting a silent failure in which a wireless terminal fails to connect to a base station even when the wireless terminal can receive broadcast information from the base station as a result of the failure occurrence in a wireless communication function of the base station is known. Namely, after failing to connect to a first base station included in a first network, a wireless terminal transmits failure notification information indicating that it has failed to connect to the first base station to a second base station included in a second network that is different in access method from the first network. Upon receipt of the failure notification information from the wireless terminal, the second base station transmits alarm information to a specified network device. The specified network device detects the silent failure of the first base station in accordance with the alarm information from the second base station.
In addition, the following technology for preparing a failure occurrence area map which indicates an occurrence location of a communication failure is known. Namely, a position information acquisition unit of the base station periodically acquires position information of a wireless terminal. A position information memory unit stores the acquired position information in a memory device. A communication failure detection unit detects the communication failure of the wireless terminal. When a communication failure is detected, a transmission unit transmits, to an area map preparing device, area map preparing information including the latest position information stored in the memory device of the wireless terminal in which the communication failure is detected. A reception unit of the area map preparing device receives the area map preparing information including position information at the time when the communication failure occurs in the wireless terminal. The area map preparing unit plots the position information included in the received area map preparing information, thereby preparing the failure occurrence map which indicates the communication occurrence location.
Furthermore, the following technology for a mobile node to estimate a location of a communication failure in the case when communication with other mobile nodes ceases is known. That is, the mobile node is provided with an information acquisition unit to acquire its own location, a memory unit to store the position information acquired by the information acquisition unit and position information received from other mobile nodes for each mobile node, a wireless communication unit to transmit position information to other nodes, and a failure occurrence location estimation unit to estimate a location at which a communication failure occurred by using the position information stored in the memory unit when the communication with the other node wirelessly connected to itself ceases.